In general, a container cover is sized to match an inlet of a container to which the container cover is applied. For example, in case that a food container has a circular inlet, a container cover is made of plastic and so fabricated that it can be fitted into the circular inlet.
Like this, it has been required to provide a structure having cover and container inlets fitted with each other in order to prevent the leakage of contents.
This means that the respective containers must use their own covers.
In practice, many containers are not provided with their own covers. Such containers generally adapt a different method for preventing the leakage of contents. For example, a wrap film made of vinyl is frequently used at a restaurant or household to seal a vowel or container containing contents such as hot soup so that the contents do not leak out of the container.
According to the above method, since the wrap film is disposable, unnecessary waste occurs. In addition, since the wrap film can be easily torn, it is used by an unnecessarily great quantity to prevent the possibility of tearing.
There are also problems in that the wrap film covering hot soup contained in the container can easily tear and more than anything else it is not easy to remove the wrap film from the container.
Further, since the wrap film is disposable, a great quantity of waste is produced, causing a serious environmental problem due to the material property of the wrap film.